This invention relates to a method of manufacturing a deflection unit for a cathode ray tube, which method comprises the step of mounting a set of saddle-type deflection coils on a surface of a hollow synthetic material coil support. The invention further relates to a deflection unit made in accordance with the novel method of the invention.
In this respect deflection unit is understood to mean a deflection unit for deflecting an electron beam in the horizontal direction, in the vertical direction or in both directions.
The invention particularly relates to the step of mounting the self-supporting deflection coils (referred to as saddle coils) for deflection in the horizontal direction on the inner surface of a coil support, but the invention is not limited thereto.
In practice, deflection coils have hitherto been mostly mounted (positioned and fixed) on an inner or outer surface of the coil support mechanically, for example, by means of snap connections, projections or other auxiliary means. A drawback of these methods is that the coils are forced to adapt their shape to the shape of the coil support and/or to the shape of the auxiliary means. Tolerances between the support and the coils and differences in expansion between the coils and the support will adversely influence the reproducibility of the deflection fields generated by the deflection units obtained: there will be spreads. Methods in which positioning means such as projections are used for positioning the coils during the mounting operation and in which glues are used for fixing do not provide a substantial improvement in this respect.